Taking the question as asked, rather than the general version of it. The escalation order that reflects the mechanism: water and salt first, then soluble fiber, then magnesium or an osmotic agent, then a stimulant only briefly and only if the osmotic has failed. Stimulants first is the commonest error and the one most likely to end in a cycle of dependence.
I added fiber, made it noticeably worse, and only later worked out that I had added the bulk without adding the water.
The question I want answered is what the mechanism is, because if it is transit rather than water then fiber is the wrong lever.
Practical detail welcome, however dull — the duller the better.
DebRD_ATL said:The escalation order that reflects the mechanism: water and salt first, then soluble fiber, then magnesium or an osmotic agent, then a stimulant only…
Acid reflux and constipation: I developed GERD symptoms around week 4 that I'd never had before. The delayed gastric emptying means food and acid sit in your stomach longer.
Management that works for me: elevate head of bed 6 inches, don't eat within 3 hours of lying down, avoid trigger foods (tomato, citrus, spicy, chocolate), and famotidine 20mg at bedtime. Much better now.
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Shop Reference Standardsandrew_nyc said:I added fiber, made it noticeably worse, and only later worked out that I had added the bulk without adding the water.
This matches mine closely enough to be worth saying so. Fiber trials in this population are thin, and most of what gets quoted is extrapolated from idiopathic constipation in people eating normally. The extrapolation is not unreasonable but it is an extrapolation, and it fails specifically for insoluble fiber at low intake — the case that comes up here most often.
Clinical perspective, offered as context rather than as advice.
Gastric emptying studies and constipation: semaglutide delays gastric emptying by ~40% at steady state, as measured by acetaminophen absorption testing and scintigraphy[1].
Clinically relevant implications:
- Explains early satiety and nausea
- Affects absorption of co-administered oral medications
- Creates aspiration risk for procedures under anesthesia
- Contributes to constipation via slowed GI transit
Importantly, the gastric emptying delay attenuates with continued use (tachyphylaxis), which correlates with the transient nature of GI side effects.
[1] Blundell J, et al. Diabetes Obes Metab. 2017;19(9):1242-1251.